We analyzed adaptation mechanisms regulating systemic inflammatory response of the stressed body by using an experimental challenge of repeated exercise bouts and accompanying muscle inflammation. Eight untrained men bicycled at 90 W for 90 min, 3 days in a row. Exercise induced peripheral neutrophilia with a leftward shift of neutrophil nucleus and neutrophil priming for oxidative activity determined by luminol-dependent chemiluminescence. Plasma growth hormone and interleukin-6 rose significantly after exercise and were closely correlated with the neutrophil responses. Serum creatine kinase and myoglobin levels as muscle damage markers rose after exercise in "delayed onset" and were closely correlated with the preceding neutrophil responses. These exercise-induced responses were strongest on day 1, but the magnitude gradually decreased with progressive daily exercise. In contrast, the magnitude of catecholamine responses to exercise sessions gradually rose, possibly suppressing neutrophil oxidative responses. These results indicate that stress-induced systemic release of bioactive substances may determine neutrophil mobilization and functional status, which then may affect local tissue damage of susceptible organs.

To investigate the cause of disagreement within the large body of literature concerning the effect of exercise on the capacity of circulating neutrophils to produce reactive oxygen species (ROS), 10 male endurance-trained athletes underwent maximal exercise. The generation of superoxide radical (O2-.) by neutrophils was first detected on a cell-by-cell basis by using histochemical nitro blue tetrazolium tests performed directly on fresh unseparated blood, which showed that responsive neutrophils under several stimulatory conditions relatively decreased after exercise. Similarly, O2-. detected with bis-N-methylacridinium nitrate (lucigenin)-dependent chemiluminescence (CL) of a fixed number of purified neutrophils on stimulation with opsonized zymosan was decreased slightly after exercise. In contrast, the 5-amino-2,3-dihydro-1,4-phthalazinedione (luminol)-dependent CL response of the neutrophils indicative of the myeloperoxidase (MPO)-mediated formation of highly reactive oxidants was significantly enhanced after exercise. It therefore suggests that the pathway of neutrophil ROS metabolism might be forwarded from the precursor O2-. production to the stages of more reactive oxidant formation due to the facilitation of MPO degranulation. In addition, these phenomena were closely associated with the exercise-induced mobilization of neutrophils from the marginated pool into the circulation, which was mediated by the overshooting of catecholamines during exercise. These findings indicate that the use of different techniques for detecting ROS or the different stages of neutrophil ROS metabolism could explain some of the disparate findings of the previous studies.

We investigated whether there is a break point of creatine kinase (CK) release after daily endurance exercise and whether CK response depends on individual physical characteristics. Fifteen healthy young men performed 90 min of bicycle exercise for 3 consecutive days. Body composition, properties of the quadriceps femoris muscle (QFM), and aerobic and anaerobic capacities were estimated before the test. Blood samples were obtained 22 times during the experimental period. Endurance exercise significantly elevated serum CK from 3 h after the first exercise session ( P < 0.05) and gradually increased thereafter. Subjects were classified into two groups according to their peak CK values: high responders (HR; >500 IU/l of CK) and low responders (LR; <300 IU/l of CK). Peak CK values during the experimental period correlated ( P < 0.01) with workload/cross-sectional area of the QFM ( r = 0.658), workload/volume of the QFM ( r = 0.648), and knee extensor strength/body mass ( r = −0.634); however, the HR and LR groups were separated in each variable. Thus the break point of CK release after endurance exercise under these conditions is 300–500 IU/l, two or three times higher than in the resting condition, and is associated with properties of the QFM.

Whereas endurance exercise is known t o induce marked neutrophilia, it remains to be fully understood as to whether the cell functions are altered as well as whether the adaptability of the responses to training occurs. To address both of these issues, we undertook the present longitudinal investigation in ten healthy untrained men (20-24 years, WQmax 39.1 *4.2 mljkglmin). The exercise protocol was 7 consecutive sessions of the same workload performed each day for 1.5 h at an intensity of 70 % of V0,max. Peripheral blood samples were obtained before, immediately after. and 1 h after exercise on Days 1, 4. and 7, and served for determination of total and differential leukocyte counts, chemotaxis and chemiluminescence of neutrophils. Acute endurance exercise caused marked peripheral neutrophilia with significant Increase in both absolute number and relative proportion of band neutrophils (PC 0.01. respectively), indlcatlng partial recruitment of bone marrow neutrophils. While chemotaxis remained unaltered following exercise. reactive oxygen species generation of neutrophils, measured by lumlnol-dependent chemiluminescence upon stimulation with opsonized zymosan. was not only significantly enhanced following exercise (p < 0.01). but also associated with the proportional increase in band neutrophils (r = 0.727. p c 0.05). suggesting that neutrophils mobilized from the bone marrow following endurance exercise may possess higher responsiveness. On the other hand, the magnitude of the exercise-induced changes was reduced gradually by daily repeated exposure t o endurance exercise, but none of the trends were significant except the decline in resting segmented neutrophil counts (p< 0.05) at least during a 1 -wk period of repeated exercise sessions. I

We examined the hypothesis that the short, intensive exercise-induced increase in circulating neutrophil counts is affected by the interaction between the endocrine and immune systems. Twelve male winter-sports athletes underwent a maximal exercise test on a treadmill. Blood samples were collected before, immediately after (Post), and 1 h (Post 1 h) and 2 h (Post 2 h) after the exercise. The neutrophil counts increased significantly at Post 1 h ( P < 0.05) and remained significantly high even at Post 2 h ( P < 0.05), showing a leftward shift. Plasma granulocyte colony-stimulating factor (G-CSF) increased at Post ( P < 0.05), and interleukin-6 (IL-6) increased at Post 1 h ( P < 0.05). Plasma G-CSF at Post significantly correlated with the numbers of both neutrophils and stab cells at Post 1 h ( P < 0.05). Plasma IL-6 at Post 1 h levels also correlated significantly with the number of neutrophils at Post 2 h ( P < 0.05). The increase in the levels of plasma G-CSF and IL-6 after intensive exercise may play a role in the mobilization of neutrophils into the circulatory system.

We studied changes in serum opsonic activity (SOA) in male judoists who were engaged in active weight reduction. Serum immunoglobulins, complements and SOA, measured by neutrophil-associated chemiluminescence responses, were investigated 20 days, 7 days and 1 day before a competition and 5 days after the competition. In addition, muscle strength and anaerobic work capacity, as well as body composition, were also determined. A dietary survey was conducted daily during the observation period. Body weight decreased by 4.2 kg over 19 days. SOA significantly decreased 5 days after the competition, as well as the concentrations of serum immunoglobulins, complements and total proteins. These trends were noted in the marked weight reduction group (i.e. reduction weight of body fat/body fat weight before weight reduction > or = 25%) more than the slight reduction group (<25%). Depressed SOA was closely correlated with the decreased concentrations of immunoglobulins and complements. These results suggest that the decrease in immunoglobulins and complements following weight reduction is associated with reduced SOA, which might cause susceptibility to infections. This study demonstrated that such immunosuppression appeared in the recovery period after the competition rather than immediately before the competition.

We examined the influence exerted, through disuse of the hindlimb, on the collagen fibres of the achilles tendon in rats. With disuse the body mass decreased by 28%, and the mass of soleus muscle decreased by 20%. A decrease in the surface area and diameter was observed in the experimental group when compared to the control group. A histogram of the collagen fibres showed a decrease of the thick fibres in the experimental group. The maximum surface area of collagen fibres in the experimental group was seen to be only 43% of that of the control group. These results showed a decrease in the thickness of the collagen fibres of the achilles tendon through disuse. This seemed to suggest that resistance to tension is decreased by disuse.

The present study examined the effects of judo training on neutrophil and related functions. We measured and studied changes in the neutrophil and its related functions in 22 male university judoists immediately before (Pre values) and immediately after (Post values) a 2 h training session: reactive oxygen species (ROS) production capability, phagocytic activities (PA) and serum opsonic activity (SOA). Neutrophil count in whole blood, myogenic enzymes (creatine kinase, lactate dehydrogenase, aspartate aminotransferase and alanine aminotransferase), immunoglobulins (IgG, IgA and IgM) and complements (C3 and C4) in serum were also measured. The Post values of the neutrophil count, myogenic enzymes and IgG increased significantly compared with the Pre values. ROS production capability and SOA also significantly increased following training, although PA showed a slight decrease (but not statistically significant). Taking the findings of our previous studies into consideration, three major neutrophil or related functions, namely ROS production capability, PA and SOA, might compensate for each other to maintain the overall integrity of the neutrophil immune function, in that ROS and SOA increased to compensate for the slight decrease in PA, or PA slightly decreased to compensate for the increase in ROA and SOA after exercise.